Mechanical vibrations in solid bodies having frequency components in the audible range (16 to 16,000 Hz) are designated as structure-borne noise. The structure-borne noise generated in the machine (noise source) is transmitted from the external surfaces of the machine to the surrounding air and thus emitted as airborne noise. Machines having high power (for example, high rotation speed) often generate noises that lie in the range in which human hearing is endangered. There exists, accordingly, the task--also in consideration of legislative requirements--of keeping the noises generated by the machine, and thus the structure-borne noise, as low as possible.
A known measure consists in enclosing the machine generating structure-borne noise. Even from the enclosed machine, however, vibrations (structure-borne noise) can be transmitted to the foundation and then emitted from there as airborne noise.
A further known measure often used to prevent the propagation of structure-borne noise is an elastic mounting of the machine with the aid of spring means (rubber, steel springs), which are arranged between the machine and the machine foundation. Or, however, the machine is rigidly attached to its foundation, for example a base frame made of section beams, and the foundation or the base frame is springingly supported.
It is furthermore known, instead of an elastic or spring support of the foundation, to mount the foundation on a damping floor, for example dry sand, and thus restrict a propagation of the structure-borne noise beyond the foundation. As is proposed in the Z-VDI guideline document titled "Noise Protection through Enclosure," VDI 2711, the machine foundation and the machine can furthermore be elastically supported (dual elastic supporting). The method proposed in this guideline has, however, the disadvantage of costly and complicated construction. Above all, however, this known method has the disadvantage that, in case of imbalances occurring during operation of the machine--in particular in the case of centrifuges--the excursions of the machine can become so large that proper operation of the machine is no longer insured.